In-floor fittings such as poke-thru fittings or floor boxes are installed in openings in concrete floors to provide electrical receptacles and communication/data receptacles (or jacks) at desired locations in buildings. Source power and signal cables loosely positioned in a plenum, which is located between the ceiling of the floor below and the floor above, may be pulled from the plenum and connected with or passed through the in-floor fitting for activation of services for and on the floor above.
In-floor fittings such as poke-through fittings may include fire-stop penetrations made of an intumescent material that expands when activated by a source of heat, such as a fire below the floor. The expansion of the intumescent material effectively forms a seal within the fitting to prevent heat penetration, both physically and thermally, into the fitting.
In-floor fittings may carry electrical and/or communication receptacles in a face-up orientation and positioned below the floor surface so as to permit the insertion of plugs completely inside the body of the fitting and under the surface of the floor with the plug cords extending out of the cover through an egress point. This configuration can be accomplished in a small footprint, but requires a tall profile. For example, a cross section of such a fitting includes the required radius to transition the cord from the top of the plug to the egress point in the cover, the height of the plug, the height of the receptacle, and the intumescent material below the receptacle. The cumulative height of these elements can easily measure between four and six inches.
Profiles of concrete floor designs vary greatly. Some are uniformly thick and are created by pouring concrete over a flat form. An alternate floor structure includes pouring concrete over a convoluted “W” shape steel deck. Concrete thicknesses for this structure can range from 2-¼ inches over the crest of the “W” to more than 7 inches at the valley of the “W”. Therefore, a tall in-floor fitting profile as detailed above can extend below the surface at of such floor at its shallowest points.
Because intumescent material will expand in all directions, it is best utilized if the direction of expansion is defined by boundaries. For in-floor fittings, the boundaries that limit the direction of expansion are the interior concrete walls and typically a steel plate at the base of the structure, which direct the expanding intumescent material into the interior of the floor hole. If the in-floor fitting extends below the slab in which it is positioned, the intumescent material may expand downward and separate from the fitting and thus diminish the effectiveness of the intumescent material.
Additionally, in-floor fittings typically include covers that allow cords to pass therethrough from plugs received within the fittings. Such covers may extend up above the surface of the floor, may have doors that open up above the surface of the floor, or include uneven surfaces.